The protagonist gabriel/dracula (re)meets Carmilla and she offers to him her blood http://youtu.be/BcPlbtT07kU?t=25s

then he is cursed by it and can become her slave for eternity if he have only corrupted blood in himself while being attackedhttps://www.youtube.com/watch?v=lRLSS0hd2IM

if not, carmilla can tricks him by taking the form of his wife and let him suck her blood once again in order to control him forever.http://youtu.be/BcPlbtT07kU?t=15m29s"she was using her blood to make him loyal to her and her alone, showing a very dangerous obession."

[first post on this forum even I'm visiting it sometimes since a while, hope you appreciate it, carmilla is a perfect femme fatale]